The invention relates to a system for minimally invasive treatment of a fracture of a bone, in particular a proximal humeral or femoral fracture.
As is known, surgical therapy has a solid position in the treatment of bone fractures. As a rule, surgery is indicated when there is significant dislocation of fracture fragments, when dislocation of the fragments caused by the fracture cannot be corrected solely by repositioning, or in the case of multiple fragment-fractures. Basically surgical methods that have preference are those with the lowest degree of damage to the soft tissue and with the advantage of early post-surgical motion therapy. Therefore systems for minimally invasive therapy of bone fractures are of increased importance. However, suitable systems for minimally-invasive therapy are not available for every different type of fracture that occurs. In the case of the shoulder, in the past access from the outside of the upper arm has not been common because known surgical techniques involve the risk of injuring the circumflex nerve.
Using plates and screws is one of the standard procedures when treating fractures of the upper arm that involve the head end of the upper arm bone (also called the humerus). With these bone fractures, also called proximal humeral fractures, the plates and screws are inserted in the usual manner, that is, in a manner that is not minimally invasive, via a sufficiently large incision in the skin, which in adults is about 10 cm long. Muscular coat, muscles, and even the joint capsule of the shoulder joint must be transected in order to attach the plate to the humerus using the screws. Fracture healing is satisfactory with this method. The large surgical access imposes major strain on the shoulder, however. Since the shoulder joint does not have much of a bony guide and a thick covering of musculature surrounds the shoulder, interventions into the soft tissue of the shoulder that are required for placing the plates and screws are generally associated with substantial post-operative movement limitations.
For treating proximal humeral fractures, so-called intramedullary nailing has become known as a particularly gentle method for avoiding damage to soft tissue. In this case, after the bone marrow cavity has been opened, thin nails are inserted, via a small incision just above the elbow, in the medullary space up to the upper end of the humerus past the site of the fracture. However, this method is only suitable for a few very simple types of fractures. In fractures with a plurality of fragments, the nails migrate upward through the open bone sites in the fracture area and cause problems in the joint.
A system called the “dynamic hip screw” has become known for treating fractures that affect the hip-end of the upper leg bone (also called a proximal femur fracture). This system is used to join a bone fragment to the non-fractured part of the bone. The dynamic hip screw system has a screw that, after creating a corresponding bore, is screwed into the bone fragment. The screw is dimensioned such that its entire length is received in the bore. The free end of this screw is fixed using a plate that is screwed to the bone. At its one end, the plate has a tube-shaped section arranged at an angle to the longitudinal axis of the plate. Prior to fastening the plate to the bone, this section is guided into the bore of the bone in order to receive and fix the free end of the aforesaid screw. However, the dynamic hip screw system cannot be used in a minimally invasive manner. It is also not suited for treating humeral fractures.
A system for minimally invasive treatment of a fracture of a bone is also known in accordance with U.S. Pat. No. 5,429,641. In this case, “long screws” are inserted via a connecting section in a sleeve in the bone. The system of “long screws” is constructed anti-tilt and axially displaceable, but only while being screwed into the bone. It is disadvantageous that after the screws are set it is a rigid connection that comprises tension and that does not permit axial displacement after installation.